Print roll composition



Patented June 21, 1938 UNITED STATES PATENT OFFECE This inventionrelates to improved print roll compositions and more particularly tosuch compositions containing a, softener comprising a mixture ofsorbitol and diethylene glycol.

The principal object of this invention is to provide a print rollcomposition having, under average conditions, a life several times thatof known print roll compositions.

Another object of this invention is to provide a print roll compositionwhich displays greater resistance to change in atmospheric conditions,particularly in humidity, than the known print roll compositions.

A further object of this invention is to provide a print rollcomposition which retains its original surface without blemish when usedwith the usual type of printing inks and when washed with the usualtypes of organic solvents.

Another object of this invention is to, provide a print roll compositioncontaining a softener comprising a mixture of sorbitol and diethyleneglycol.

Still another object of this invention is toprovide a print rollcomposition accomplishing the above-mentioned objects while at the sametime overcoming the objectionably high viscosity of print rollcompositions softened with a mixture of sorbitol and glycerine withoutnecessitating the use of inordinately high percentages of water.

Heretofore, ordinary print roll compositions have comprised a binder ofgelatin or glue, a

softener and Water.

clusively used in the past has been glycerine. Print rollers made upfrom a composition comprising a softener consisting of glycerine haveproved objectionable since they display undue changes in properties uponvariation in atmospheric humidity. Such rollers absorb an excessiveamount of moisture under conditions of high humidity and give up anundue amount of moisture under conditions of low humidity. Theconsequence is that their physical characteristics such as length,diameter, hardness, tack, etc., vary to an objectionable extent withchanges in humidity. These changes in physical characteristics are sogreat that rollers made from glycerine-softened compositions must bedesigned for use in a certain season and cannot be used outside of thisseason. However, this does not always cure the defect since atmospherichumidity changes considerably even during the same season with theresult that such rollers are not always usable in the season for whichthey were designed.

PRINT ROLL COMPOSITION Leander H. Harrison, New York, N. Y., assignor,

by mesne assignments, to Atlas Powder Company, Wilmington, Del., acorporation of Delaware N Drawing. Application August 12, 1937, SerialNo. 158,759

13 Claims. (Cl. 106-55) Another outstanding disadvantage of the priorprint roll compositions softened with glycerine is that rollers madetherefrom have an objectionably short life. Still another disadvantageof such print roll compositions is that they vary in physical propertieswith variations in temperature. The result is that rolls made for lowtemperature operation are unduly soft if used under conditions of hightemperature. On the other hand rolls made for high temperature operationare unduly hard and lack the proper resilience under conditions of lowtemperature.

It has been proposed to use as the softener for the glue or gelatin of aprint roll composition a mixture of. sorbitol and glycerine containingnot over 75% of sorbitol. Such use results in a composition having amuch longer life than use of a softener consisting of glycerine. Howeverthe compositions have been extremely viscous at pouring temperature. Inorder to reduce the viscosity the percentage of water in the compositionmay be increased but this results in excessive shrinkage after castingwhich shrinkage culties.

I have found that the use in print roll compositions comprising a binderof glue or gelatin, 2. softener, and water, of a softener consisting of65 to 85% sorbitol, the balance being of diethylene glycol, producesexcellent print rolls and overcomes the disadvantages of the prior printroll compositions mentioned above. I

Instead of using pure sorbitol in the print roll composition of thepresent invention, I may use a technical sorbitol syrup such as may beobtained by the reduction of monosaccharioles such as glucose andtreatment of the reduction liquor so as to recover therefrom a Viscousaqueous syrup containing sorbitol and small amounts of impurities suchas unreduced sugar, ash, and organic impurities some of which may bemore or less closely related to sorbitol.

The composition of the softener used in the present invention may varyfrom 65% sorbitol and 35% diethylene glycol to 85% sorbitol and 15%diethylene glycol. The use of less than 65% of sorbitol produces acomposition which lacks firmness of body to such an extent that it isunsuitable for use as a print roll. The use of more than 85% of sorbitolproduces a composition which case hardens and is too hard surfaced to beuseful. The highly preferred proportion is 75% of sorbitol and 25% ofdiethylene glycol. These percentages are by Weight and are on awater-free basis.

The softener almost exis difficult to predict and otherwise involvesdiffi- The ratio of the softener to glue may vary with the compositionof the softener (proportions of sorbitol and diethylene glycol) and withthe quality of the glue. It may also vary to some extent with changes inwater content. Using a good grade of hide glue. and a softenercontaining between 65 and 85% of sorbitol the ratio of softener to gluemay vary from 3 to 1 to 1 to 1. When using a softener containing 75% ofsorbitol and 25% of diethylene glycol, a ratio of softener to glue ofabout 1.75 to 1 produces excellent results, making a roll which issuitable for a range of temperatures and which is better for variableweather conditions. To render the composition more resistant tosoftening to heat, especially where extremely high temperatures are tobe encountered, this ratio may be 1 to 1 or even as low as .5 to 1. Forgreater softness and resiliency or where extremely low temperatures areto be encountered it may be as high as 3.0 to 1.

The moisture content of the ultimate print roll composition issusceptible to considerable variation but is preferably maintained atnot over 30% in order to avoid excessive shrinkage particularly in dryatmospheres and at not under 10% in order to produce a composition whichcan be readily handled and worked. The preferred range of moisturecontent is from 15 to 22%. Within this preferred range a moisturecontent of 20% has been found to be extremely suitable. The moisturecontent of the finished roll will vary to some extent with changes inhumidity, increasing during periods of high humidity and decreasingduring periods of low humidity, although not nearly to the same extentas a glycerine softened roll.

In order to produce a composition containing this preferred content ofmoisture, I take into consideration the fact that in the preparation ofthe composition the use of the required heat causes considerable of theinitially added water to be evaporated. Consequently such an excess ofwater over the calculated amount is added at the beginning of theoperation that the ultimate compositions will have the desired moisturecontent. As an alternative to this method of compensating for loss ofwater by evaporation, I may add water during the preparation in anamount equal to that evaporated so as to maintain constant Weight and soas to prepare a finished composition having the required moisturecontent.

Non-limiting examples of print roll compositions comprehended by thepresent invention are given below. While these examples involve specificproportions these are given for purposes of illustration only and it isto be understood that other and equivalent proportions may be used. Thusthe water content and the ratio of softener to glue may be varied withinthe limits discussed above.

Example 1 Percent Glue (dry basis) 29. Softener (dry basis) (75%sorbitol-45% diethylene glycol) 51. 0 Water 20.0

Example 2 Glue (dry basis) 29.0 Softener (dry basis) (70% sorbitol30%diethylene glycol) 51. 0

Water 20.0

Example 3 Percent Glue (dry basis) 29.0 Softener (dry basis) (66sorbitol-33 diethylene glycol) 51.0 Water 20.0

Example 4 Glue (dry basis) 29.0 Softener (dry basis) (85% sorbitol15%diethylene glycol) 51.0 Water 20.0

Example 5 Glue (dry basis) 32.0 Softener (dry basis) (75% sorbitol-25%diethylene glycol) 50.0 Water 18.0

The compositions of the foregoing examples were prepared by weighing thediethylene glycol, sorbitol, and water into a hot-water jacketed orsteam jacketed kettle and heating to a temperature of 70 0., replacingany evaporated water, adding the glue with stirring and cooking withoccasional stirring at 70 to 80 C. for two hours or until free from gluegrains. Evaporated water was again replaced and thoroughly stirred intothe mixture. The composition was then poured into the mold.

Other and equivalent procedures may be used, however, and the foregoingprocedure is not to be considered as limiting. The ingredients may becommingled in different order into a homogeneous mixture, and the amountof water added at the beginning of the procedure may be sufficient so asto make unnecessary the replacement of evaporated water as theformulation proceeds. The amount of water remaining at the end of theoperation should be suffioient to permit handling and molding of thecomposition and preferably should fall Within the ranges above setforth.

An advantage of compositions formulated in accordance with the presentinvention is that with the same water content they are less viscous thancompositions softened with a mixture of less than 75% sorbitol and thebalance of glycerine. The composition of Example 1 is illustrative inthat it had a viscosity of 7200 centipoises at 75 C. as compared with aviscosity of 7900 centipoises at 75 C. for a composition containing 29%glue, 51% softener composed of 55% sorbitol and 45% glycerine, and 20%water, and therefore was much more readily manipulated. This enables oneto maintain the water content at such an amount that excessive shrinkagedue to larger water content is avoided, while the composition is asreadily manipulable as compositions softened with a mixture of sorbitoland glycerine, with larger water content and being therefore moresusceptible to shrinkage. At the same time, the composition of theinvention has sorbitol present in sufficient amount to give thecomposition increased resistance to the abrasive action of type and toattack by organic washing solvents, and reduced susceptibility to changeduring extreme variations in atmospheric conditions. Further, thecompositions of the present invention may be prepared with a lower ratioof softener to glue without the necessity of using an excessive quantityof water.

It will be seen from the foregoing that I have devised a new print rollcomposition having marked advantages over prior print roll compositions.

Having described my invention, what I claim is:

1. A print r011 composition containing a binder, a softener and water,said softener comprising sorbitol and diethylene glycol, the sorbitolbeing present in an amount not less than 65% and not more than 85% ofthe total softener content.

2. A print roll composition as recited in claim 1 and wherein the wateris present in an amount not exceeding by weight of the composition.

3. A print roll composition as recited in claim 1 and wherein the wateris present in an amount in the neighborhood of from 15 to 22% by weightof the composition.

4. A print roll composition containing a binder, a softener and water,said softener comprising sorbitol and diethylene glycol, the sorbitolbeing present in an amount equal to 75% of the total softener content.

5. A print roll composition as recited in claim 4 and wherein the wateris present in an amount not exceeding 30% by weight of the composition.

6. A print roll composition as recited in claim 4 and wherein the wateris present in an amount of from 15 to 22% by weight of the composition.

'7. A print roll composition containing a binder, a softener and water,the binder and softener being present in said composition in a ratio ofone part binder to from 1 to 3 parts softener,

said softener comprising sorbitol and diethylene glycol, the sorbitolbeing present in an amount not less than and not more than 85% of thetotal softener content.

8. A print roll composition as recited in claim. 7 and wherein the wateris present in an amount not exceeding 30% by weight of the composition.

9. A print roll composition as recited in claim 7 and wherein the wateris present in an amount in the neighborhood of from 15 to 22% by weightof the composition.

10. A print roll composition containing a binder, a softener and water,the binder and softener being present in a ratio of one part binder from1 to 3 parts softener, said softener comprising sorbitol and diethyleneglycol, the sorbitol being present in an amount equal to of the totalsoftener content.

11. A print roll composition as recited in claim 10 and wherein thewater is present in an amount not exceeding 30% by weight of thecomposition.

12. A print roll composition as recited in claim 10 and wherein thewater is present in an amount in the neighborhood of from 15 to 22% byweight of the composition.

13. A print roll composition comprising a homogeneous mixture of 29.0%glue, 51% of a softener and 20.0% of Water, said softener consisting of75% of sorbitol and 25% of diethylene glycol.

LEANDER H. HARRISON.

\ CERTIFICATE OF CORRECTION. Patent No 2,121,126. June 2L 1958o LEANDERH. HARRISON.

Ibis-hereby certified that error appears in the printed specification ofthe above numbered-patentrequiring correctionas follows: Page 5, secondcolumn line 16, claim 10, after the word "binder" insert to; and thatthe said Letters Patent should'be read. with this correction thereinthat the same may conform to the record 'of the case, in the PatentOffice.

Signed and sealed this 9th day of August, A. D. 1958.

Leslie Frazer (Seal) Acting Commissioner of Patents.

